The impact of immunochemical faecal occult blood testing on colorectal cancer incidence.

BACKGROUND: The efficacy of colorectal cancer screening based on faecal immunochemical test, in terms of reduction of colorectal cancer incidence, is under debate. In the district of Florence, an organized screening programme based on faecal immunochemical test has been running since the early 1990s. The aim of this study was to compare the risk of developing colorectal cancer for subjects undergoing faecal immunochemical test with those who did not undergo the test in the same period. METHODS: Two cohorts were analyzed: subjects who underwent an initial faecal immunochemical test between 1993 and 1999 ("attenders"), and unscreened residents in the same municipalities invited to perform the faecal immunochemical test in the same period ("non-attenders"). Kaplan-Meier and Cox regression analysis were performed to evaluate the risk of developing colorectal cancer. RESULTS: The attenders' and non-attenders' cohorts included 6961 and 26,285 subjects, respectively. Cox analysis showed a reduction in colorectal cancer incidence of 22% in the attenders' compared to the non-attenders' cohort (hazard ratio = 0.78, 95% Confidence Interval: 0.65-0.93). CONCLUSION: Our results support the hypothesis that screening based on a single faecal immunochemical test every 2 years produces a significant decrease in colorectal cancer incidence after an average follow-up observation period of 11 years.